The South Dakota Badlands has a long history. About 75 million years ago, the land was underwater as part of the Western Interior Seaway. During the next 50 million years, the continent buckled several times. Each event led to an uplift until the sea was drained about 28 million years ago resulting in the Sharps Formation. Rivers then relentlessly carved the landscape. Volcanic activity produced layers of ash. During the last major uplift 4.5 million years ago, sediment from the nearby Black Hills flowed into the area. Each timeframe left behind layers of soil, rocks and fossils. This process is called deposition. About 500,000 years ago, the wind, rain, snow and sun began eroding this geological soup. Soft material disintegrated the fastest. Hard rock was more resistant. The results are what you admire today at the Badlands National Park. This spectacular scenery is work in progress. It erodes at the rate of one inch per year. Within another half million years, most of the rock formations will be gone.